Wireless LANs A wireless LAN uses wireless transmission medium To satisfy requirements for – mobility – relocation – ad hoc networking – coverage of locations difficult to wire WLANs were little used for their high prices, low data rates, occupational safety concerns, and licensing requirements. As the above problems have been addressed, popularity of wireless LANs has grown rapidly.

Applications - LAN Extension Saves installation of LAN cabling Eases relocation and other modifications to network structure However, increasing reliance on twisted pair cabling for LANs – Most older buildings already wired with Cat 3 cable – Newer buildings are prewired with Cat 5 Wireless LAN to replace wired LANs has not happened In some environments, role for the wireless LAN – Buildings with large open areas Manufacturing plants, stock exchange trading floors, warehouses Historical buildings Small offices where wired LANs not economical May also have wired LAN – Servers and stationary workstations

Example Single-Cell Wireless LAN Configuration

Applications – Cross-Building Interconnect Connect LANs in nearby buildings Point-to-point wireless link Connect bridges or routers Not a LAN by itself – Usual to include this application under heading of wireless LAN

Applications - Nomadic Access Link between LAN hub and mobile data terminal – Laptop or notepad computer – Enable employee returning from trip to transfer data from portable computer to server Also useful in extended environment such as campus or cluster of buildings – Users move around with portable computers – May wish access to servers on wired LAN

Applications – Ad Hoc Networking Peer-to-peer network Set up temporarily to meet some immediate need E.g. group of employees, each with laptop or palmtop, in business or classroom meeting Network for duration of meeting